The grass rules in Cambridge

This picture was taken on the 31st of July 2018 at Downing College. Do you see anything other than the yellowy grass? Well here is the hint:
* The man with the white shirt is walking furiously towards the men. * The white shirt man is the porter of the college * The men are tourists

Yes, this is actually a scary situation to Cambridgians because only 1) fellows, 2) people talking to a fellow, 3) gardener including gardening robots, and 4) ducks are allowed to walk on college grass.

So, I would encourage tourists to read the dos and don’ts before coming, otherwise you will porters yelling at you!